Add wait/hourglass cursor implementation via XC_watch

This adds support for the wait/hourglass cursor shape on X11 using XC_watch

src/x11_window.c

@@ -123,6 +123,8 @@ static int translateCursorShape(int shape)
             return XC_sb_h_double_arrow;
         case GLFW_VRESIZE_CURSOR:
             return XC_sb_v_double_arrow;
+        case GLFW_WAIT_CURSOR:
+            return XC_watch;
     }
 
     return 0;